Oil filter



Jan. 8, 1946. A, G F WALLGREN 2,392,348

OIL FILTER Filed Oct. 23, 1940 2 Sheets-Sheet 1 Jan. 8, 1946.

A. G. vF. WALLGREN OIL FILTER Filed Oct. 23, 1940 24 Sheets-Sheet 2 mf vf/v roe. MM @gufi 6.' M ArToR/vx ter is rendered incomplete.

.the filter spaces, which involve an increased re- Patented Jan. 8, 1946 OIL FILTER.

August Gunnar Ferdinand Wallgren, Eskilstuna,

Sweden,

assignor to Aktebolaget Bolinder- Munktell, Eskilstuna,-Sweden, a corporation of the Kingdom of Sweden Application October 23, 1940, Serial No. 362,326

Sweden November 8, 1939 5 claims. 5.01. 21o- 167)y Oil filters made from textile material can without' diiiiculty be made sufficiently line-meshed to ensure a far` carried puriication'of the oil. Such textile lters have many drawbacks, however. terial decays in the oil, and, furthermore, the meshes are clogged up by 'water which may be comprised in combustible oil, for example. All this has contributed toward the fact that metal filters are nowadays resorted to more and more. In this type of filter, however, other difficulties are met with, among other things with respect to the cleansing capacity of the filters.

It is one essential object of the invention to make it possible to purify the oil to such an extent, without the same being subjected to an inadmissi-bly high fall in pressure within the filter, that the remaining particles in the oil, should the latter Ibe intended for the lubrication of frictional bearings, for example, will have a diameter smaller than the thickness of the film in these bearings. Thus the particles which are not separated in the filter shall be able to pass through the bearing without causing any detrimental eect on the bearing surfaces. Correspending demands are made onk the degree of purification in filters adapted for instance for combustible oil having to pass through a fuel nozzle. Hitherto, metal lters were constructed consisting, among other things, of spirallxwound thin sheet metal strips with a spacing of the convolutions of the winding of about 0.03 mm., which does not give a satisfactory filtration of the oil. The oil resistance, which will be particularly great in this case by reason of the great space length in the direction of flow of the oil, would at still less rwidths ofthe space exceed practically suitable values. To reduce the resistance of the lter it has also been suggested to make use of metal wires Wound adjacent to each other with a spacing determining the cleansing capacity of the filter.

When continuously 'used the filter is to be cleaned, for which purpose it is known to employ brushes that scrape over the elements or the wire winding on rotating a'drum carrying the same. In this way, the cleansing of the fil- Particles remain in sistance to the oil, because the points of the bristles cannot penetrate down into these spaces, particularly if they are very small. It was therefore necessary to make the width of the space comparatively great, if any cleansing effect were to be Vreached at all-without the filter' becoming They are difficult to clean, the iilter maclogged up. It is also known to provide a flow of oil opposite to that of normal filtering through the spaces of the lter in order to remove particles collected thereon. This counterilow is effected in a mechanical way' by establishing a pressure higher than the oil pressure in the lter. This known construction is, however, relatively complicated and moreover a reliable cleansing cannot be ensured as particles after being removed from the iilter are floating in theoil, which is on the way to the iilter,` whereby such particles are again deposited there. Moreover, it is difcultto provide a counterilow of sufficient eiecti-veness to ensure a proper cleansing.

In accordance with the invention, a `rotatable drum carrying the filter means, such as wires, communicates over a portion of its periphery with a chamber in which a pressure lower than the oil pressure in the lter means is prevailing, so that a counterilow is set up in that portion of the drum, which during the rotary movement is momentarily in alignment with the chamber. An efficient cleansing is in this way ensured independently of the width of the spaces between the Wires, and consequently said widthmaybe reduced to the small dimensions stated hereinabove. The oil lter is rendered exceedingly safe in operation while it will at the same time be capable of relieving the oil even of very small impurities. The wires may have a diameter as small as 0.1 mm. and less, whereby the resistance to flow is reduced in a 'very high degree. Moreover, the dimensions of the lter become small in comparison with previous constructions. In modern motors provided with forced circulation lubrication and cooling of the bearings and pistons or the like, the quantity of oil to be cleansed by the lter per unit of time will be many times greater 1 than previously. The oil filter produced in accordance with the invention is well apt to answer the increased demands. v

Further objects andadvantages of the invention will be apparent from the following description considered in connection with the accompanying drawings which form a part of this speciiication, and of which:

Fig. 1 is a longitudinal section taken on'the line I-I in Figs. 2 and 5 'through an oil lter constructed in accordance with the invention;

Fig. 2 is a section taken on the vline II--II of Fig. 1;

Fig. 3 shows detail in the same section as in Fig. 2 but on anenlarged scale;

Fig. `i is a section taken on the line IV-IV ofFig. 2; D.

for rotating the oil lter; the gure being a sec-` '5 tion taken on the lines VI-VI of Figs. 7-9;

Figs. 7-9are sections taken on the lines VII- VII, VIII-VIII, and IX-lX, e respectively, of Fig. 6;

Fig. 10 shows a longitudinal section through a I0 portion of an oil lter according to a further ern-L bodiment of the invention; the gure being a.v section taken on the lines X-X of Figs. 11-13 Figs. 11-13 are sections taken on the lines XI-Xl, XII-XII, and XIII-XIII, respectively, l1u;

of Fig. 10.

In the drawings, 29 designates avpreferably cy-; lindrical casing which is rigidly connected to aframe, such as a motor casing 22, Iby means of a liange 2|. the casing 29 and in a cover 23 rigidly connected Y withV the frame, said shaft having a drum'25 se` curedV thereto. The drum is connected with the shaft over a number of hub portions 26 Ypermitting a free axial passage of the oil within the 25 A drum. The outer periphery of the drum 25 is Vformed witha, plurality of longitudinally extend-y ing groove-shaped recesses21, each communicating withv the interior of the drum, preferably through a plurality of apertures 28. A metalwire 30 29, preferably Vfrom stainless steel, is wound about the drum so vas to bear on the outer edge of the walls39 (Fig. 3) between each pair of recesses 21,

l ,Y The wire 29 has a diameter ofA` the size of 0.1;35 mm. It is wound about the drum in a manner such that there will be a space between Ythe Wire convolutions which is preferably less than 9.025

, mm., preferably about 0.01 mm. The winding is k preferably eiected with the aid of a machine pro,- glo vided with a feeding device, such as a lathe, so

` that the wireis subjected to a certain tension so as tobe embedded intothe outer` edges of the y walls 39., The drum 2,5 may be made from rela- Y tively soft materialgsuch as brass.

Asleeve 3| having recesses 32 separated by walls compartments limited bythe lattergwill be s eparated from one another in the peripheral di-y rection. Likewise, the outer sleeve 3| is preferably provided with a number of apertures for 55 each recess 32 which communicate with a space 36 between the sleeve and thel outer casing 20.

A plunger 3l (Fig. 2) isprovided in the casing 20 andV is pressed against the cylindrical outer surface ofthe sleeve 3| with the aid of a spring 60 38 and by the oil pressure acting upon the same. The plunger 3 1 bears on the sleeve 3| with two projections 39 which are spaced ln the peripheralrdirection about equal to the spacing of the apertures 35 in the sleeve 3|, as will appear from 65 'Y the wire winding will .communicate with the Fig. 2. A chamber 40 which is limited laterally by the projections 39 communicates with anout- 'let conduit through a passage 4| in the sleeve.

VThe plunger Y3l is guided 'by a boss 42. v

The oil to be cleansed isintroduced, for in- 70 stance, by means of a pump, through a passage 43 in the elements 22, 2|'to the inside ofthe cover 23 and thence to the above-mentioned space A shaft 24 is rotatably mounted in 20 and the same recess are brought every time into the drum 25 through' a passage 44. Provided between the passages 43 and 44 Vis a sleeve valve 45 which is normally closed. The valve 45 is then under the pressure of a spring 45. However, should the drop in pressure within the lter become too great, for instance by the oil being kcold at the starting of the motor, the valve 45 will be opened while overcoming the resistance 'of the spring, so that the oil may be conveyed momentarily past the lter to the outlet 44.

The shaft 24, together with the elements 25, 3| connected therewith, and the wire winding 29 are driven in the embodiment according to Figs. 1-5 by a gear wheel motor consisting of two gear wheels 59 of a construction known per se, the shafts 5| of which are Vcarried yby bearings 52, 5,3. 'Thesegbearings are provided in the casing 29 and. in an annular element 54 rigidly connected therewith. One of the shafts 5| communicates over a gearing 55, 55 with the shaft 24. The said gearing is enclosed within a cover 5l. Oil. under pressure is supplied to the gear wheel motor from the insiderof the drum 25 through a conduit 58, and escapes through a conduit 59. Members for the control of vthe oil quantity passing through vrthe motor may be provided in the outlet conduit.

The device operates in the following manner. The impure oil entering the space 36 between the sleeve 3| andthe frame 23 flows through the apertures'35 into the chambers 3'2 and then passes through the line spaces .between the windings of the wire 29, the solid particles comprised in the oil being thenV separated on the outside of the wire. The clean'oil continues through the spaces 2l, the openings 28, the interior ofthe drum 25 to the outlet conduit Y44.

Filtered'oil is taken from the inside of the drum to operate the gear wheels 59. The shaft 24 with theelements 25 and 3| is rotated at aproperly determined, relatively slow rate of speed. On rotation of the elements 25, 3| the openings 35 pass successively past the chamber 49, whereat, as will be seen from Fig. 2, only that opening or those openings which communicate with one communication with this chamber. While a pressure above atmospheric prevails in the interior of the drum 25, the pressure within the chamber 49 is lower for the reason that the passage 4| is L open communication with the atmosphere or with a collecting space or the like. During the K time in which an opening 35 thus moves past the vchamber 43, a flow of oil will be produced in a direction opposedto the direction during filtration through the portion of the wire winding 29 lying inside theV opening, that is to say, from the interior of the drum 25 and outwardly through the space 2l, the fine Vspaces between Ithe wire convolutions, the 'space 32, and the opening 35. The. solid particles'adhering to the outside of the wire winding are then washed oil to escapev with theol] through' the passage 4|.v It Will appear from the above that forevery revolution only a small portion of the peripheral circumference of cleansing chamber 40., The spaces 2l, 32 are separated laterally from each other by the walls 39, 33, sothat only the portion of the wire winding being between two such pairs of 'walls will at the same time be brought into communication with the outlet chamber 49. In the present case, there are twelve such spaces 2l, 32, from which it will be seen thata twelfth of the wire winding at atmewilkbefsubiected to-.cleansingl Accord- 'lng to the invention, .the filteris self-cleansing and operates altogether automatically. If desired, a number of chambers 40 may bearranged behind one another, one for eachopeningi35 pertaining to one and the same space121, 32. f

In the embodiment above described, the hydraulically operating driving mechanism is adapted .to drive the filter drum continuously vin one and the same direction. Figs, 6-9 showamodifled embodiment of a hydraulic driving mechanism adapted to actuate the shaft 24 intermittently. Otherwise, this embodiment (like that according to Figs. 10-13),may be constructed 'in the same manner as that above described, and the same reference numerals have been used for equivalent parts. Avane piston 60 provided with avane 6| is rotatably mounted by Vmeans of a pin 62 in a lcover63. which is centered in the casing 20 and secured to the latter by means of screws 64. The vanep6| is reciprocating within a space 65 (Fig. 9), which isbounded outwardly by the casing 20 and Vinwardly by a slide 66, and in the peripheral direction by two blocks 61 connected with the casing 20 in a suitable way.

Rigidly connected with the shaft 24 is a hub sleeve 68.. This hub sleeve is provided with recesses 69 for locking rollers 10 adapted to cooperate with an eccentric roller track at the bottorn of the recesses 69 and bearing against the upper cylindrical surface of a partition 1| in the casing 20. The rollers I9 may be actuated by springs 12 tending toA move the rollers into locking position. In a similar manner, rollers 13 (Fig. 6) are provided lbetween the hub sleeve 68 and the vane piston 60. The rollers 13 and 10 are adapted to cooperate vwith the elements 60, 68 on the one hand, and with thev elements 68, 1| on the other hand, in a manner such that the shaft 24V will be driven when the vane piston moves in one direction, whereas it will be locked when the vane piston moves in the opposite direction. Thus the locking members 10, 13 are operative alternately at the movement of thev A vane piston in the one or the other direction,

' arm 15. The arm 15 serves on the opposite side `fof the pin 62 as an attachment for one end of a spring 16, the other end of which is arranged about a pin 11. The pin 11 is carried by an arm 18'which' is pivotally mounted about a pin y19 lrigidly connected with the head cover 63. v

The arm 18 carries a catch 80 entering between two projections 8| on an arm 82 Whichis rigidly connected withA the slide 86. Thus when the arm 18 moves between two abutments 83 (Fig. '1) on the cover 63, the catch 80 will in Va certain position strike against either of the projectionsl so as to Vcarry Aalong the arm 82 and the slide 66 to one of the extreme positions, as will be described more fully in the following. The arm 18 is actuated by an arm 84 which is "rigidly connected with the vane piston 60 through is less thanthat between the passages 88.` The peripheral extension of the passages 88 on the outside of the slide is of `vsuch magnitude that The ' they will in certain positions connect the space 65. on the one side or the vane 6| with outlets 89 in either of the blocks 61. Y

The device according to Figs. 6-9 operates in 5 the following manner. In Fig. 9, passages 81 and 88 are in alignment on the left hand side of thev vane 6|. Pressure oil is consequently introduced into the space 65 on the left 'hand side of the vane 6| so as to move the latter in the direction of the arrow 90. In this movement the vane piston 60 and the hub sleeve 68 is carried along as the locking rollers 13 are in their operative position. 0n the other hand, the locking rollers are inactive. The vane piston 60 also carries along the arm 84 in its rotary movement. When the vane 6| approaches the extreme position of its path of movement, the projection 86 of the arm-84 is brought into contact with the end portion 36 of the arm 18, and commences to turn this arm. When the arm 18 is brought position, it will be pulled by the spiral spring 16 toward the opposite abutment 83. The catch 80 of the arm 18 will then hit the abutment 8| on the arm 82 shown to the right in Fig. 7, and in this way carries along the slide 66 in its rotary movement, until the arm is stopped by the said abutment 83. This involves that the slide 66 is turned in a counter-clockwise direction in Fig. 9 so that the passage 88 positioned on the right hand side of the vane piston is brought into connection with the corresponding pressure oil passage 81, while the other passage 88 is brought into connection with the outlet 89 in the left hand block 61. Thus the vane 6| is now subjected to pressure on the other side thereof so as to move in a direction opposed 'to that of the arrow 90. During this return movement the shaft 24 is locked by the locking rollers 10, whereas the locking rollers 13 are released from their locking engagement. Another shifting of the slide occurs at the end of the return movement in the manner above described, whereupon the vane piston performs its next working stroke, and so forth. K The arm 15 has for its object furtherrto increase the v,turning moment .by which the arm 18`pulls the slide v66 toward the new position, The driving mechanism according to Figs. 6-9 also operates entirely automatically, as will be seen from the above, but at a stepwise rotation of the shaft 24. l

The embodiment according to Figs. 10- 11is also provided with a lvane piston 93 provided with a vane 94, which in this embodiment, however, is rigidly connected with the shaft 24 by means of a nut 95 or the like,'so that this shaft will, together with the filter drum 25, 3|, follow the vane piston in its reciprocating movement. The length of stroke of the vane piston corresponds in this case to a rotary movement of the shaft 24 alittle 'short of a complete revolution. The length of stroke is limited by an-e1e ment 96 which is rigidly connected with the stationary outer casing 20. Disposed in the vane piston 93 is aslideV 91. f Filtered oil under pressure is supplied to the space 98 (Fig. 11) having the vane 94 operating `therein, through a passage 99 and either of two passages |00 in the vane piston andV either ofntwo passages |0| in the slide 91. The oil contained in the space 98 on the opposite side ofthe vane 94 escapes through either one of the two. passages |00 in the vane piston 93 to a passage |02 in the slide 91 and over a passage, not shown, to a slot 75. |03 in the-slide. a radial passage |04in thevane over the center, that is to say the labile middle byY the rollers. i the rollers its are. guided at a suitable radial freejdcmor 'movement by* two disks H4 one of which" l movement .of the vane piston. I ileisformed with slots III entered by pins Ilo ments. Y v n lnFig. Il, the siot I on the left hand side v o the vane sois throughthe pressure oil passage piston, and finally' .to an annular groove Uli and passages VIIII in theV casing `2tlg .The quantity .of

oil and thus the rate or movementroi the vane piston are adjustable by means of aaserew IQ?.

In., embodiment, .thershifting movement betweenthe'vane. pistong and the slide 91: is

eifectedwiththe aid of a mechanism, generally Provided between 85 with pairs of recesses LIS entered alternately The holders |08 together with isconnected with a pin It engaging, a slot H5 in theV cover 63. I, The slot-.it has a peripheral extension which Vis smaller than the angle `of fromthe slide el. The grooves II permit of a small relativerotary movement between the slide and the mechanism Hi8 which is sufficient to shift the. communications between the passages Ill Y and Int. VVApin II enters from the slideL 9?' into agroo've in the vane piston 9.3, which permits ofthe same or substantially the same relative vrotary-.movernent between these two eleilI in communication with the; interior of the filter. The vane piston 93, therefore moves accordingto the arrow i253 in the same figure andy carries along the slide Sl over the pin IIB.

The rollers I09 of the shifting mechanism |08 f are in engagement with two opposed recesses I I3 in the pistonslide (see Figpl2), The pins IIS Aof the-slidea in the one extreme position 'fthe 'slots III, that is to say, so that the mecha- Vnism-IIl8 cannot be turned further relatively to the slide in the direction'of movement of the vane 9 4; When during its movement the -vanepiston is H at a certain angle from its returning position, the

pin II5 reaches the end of the slot IIB (see Fig.. V13,). ilVhile the vane piston and the slide conf tinue their rotaryA movement, the shifting mechanism 'IlY is thus stopped. This results in that the rollers los roli up tne Walls of the twoopposed grooves I'I3 with which they are in engagement. When the rollers have come up on the edge between the. pairsof grooves lI3, the slot II'I of the. mechanism I 08 will at the same time have been brought into contact with the pins IIB at the opposite end of the slots as before. The roll- Y, erslrnow strike over into the other pairs rof recesses I I3, the slide 91 being carried along and displaced relatively to the vane piston.` Through l this relative movement the pin IIB has reached the opposite vend of the slot II6 of the vane piston cooperating therewith. Furthermore, the slot m2, which previously communicated with the right hand passage |00 in the vane piston. accordf ing to Fig. 11, has been kshifted to alignment with the previously inactive supply passage IUI sothat pressure oil is introducedY to the opposite side of the vane 9d. The latter returns and then carries along the shifting'mechanism and theslide, until TheA other disk,

andasse the same shifting operation occurs` at the end of the next stroke, andso forth. The hydraulically acting motion, mechanism may be combined with a mechanically or manually operablelrotating device, In certain cases it is also conceivable to drive the filter'solely by `means of a mechanical device, although the hydraulic operation is for many reasons to be pre- Y ferred, for instance bythe fact that the filter can be placed in a motor independently of the special position ofthe rotating shafts thereof. Infilters for combustible oil, the width of. the: spaces of the filtering elements maybe still lessthan that stated hereinbefore. In such cases the wire maybe Wound .soV that the wire convolutions. are brought into direct contact with each other. V0n account of unavoidable divergencias ofthe-wire diameter, ne spaces will then be produced, which are suihcient for thepassage of the combustible oil. According to the invention, the diameter of the wire ina filter rfor lubricating oil or combustible oil is preferably less than 0.25 mm. i

While several embodiments of the, invention have been shown, it is to be understood that these are for purpose .of illustration only, and that theinvention is not to be limited-thereby, but its Y scope is to be determined by the appended claims munication with said chamber, whereby counterflow of huid takes place through successive porviewed in the light of the prior art.

What I claim isz. Y 1. In a iilter, a casing, a drum rotatably mounted within said casing, the exterior surface of said drum being formed with a plurality of axially extending grooves and' with an opening extending through the drum from eachgroove, a sleeve secured to and surrounding said drum, the interior surface of said sleeve being formed with a like number of axially extending grooves iii-alignment with the grooves in said drum, said sleeve being formed'with an opening extending therethrough from each groove therein, filter means disposed between said drum and said sleeve,

means for introducing fluid to be filtered to the outside of said sleeve, means for withdrawing ltered iiuid from the interior of said drum, means including members bearing against theY outside of said sleeve providing a chamber of limited peripheral extent adjacent thereto, means for maintain- Y ing a pressure in said chamber lower than thatY of the-ltered fluid Within said drum,l and means for rotating said drum and sleeve so as to bring the openings in said sleeve successively into comextending grooves, separatedV by ribs and with an opening extending through the drum from each lgroove, a sleeve secured to and surroundingA said drum, the interior surface of said sleeve being formed with a, oke-number of axiany extending grooves separated by ribs, the ribs on said drum bearing against the outside of said s1eeve'providy ing a chamber of limited peripheral extent adjacent thereto, means for maintaining a pressure in said chamber lower than that of the filtered fluid within said drum, and means for rotating said drum and sleeve so as to bring the openings in said sleeve successively into communication with said chamber, whereby counterflow of fluid takes place through successive portions of said iilter means from within said drum to said chamber.

3. In a iilter, a casing, a drum rotatably mounted within said casing, the exterior surface of said drurnlbeing formed with a plurality of axially extending grooves separated by ribs and with an opening extending through the drum from each groove, a lter means constituting a ne wire wound helically around said drum and imbedded in grooves formed in to the tops of said ribs, a sleeve secured to and surrounding said drum, the interior surface of said sleeve being formed with a like number of axially extending grooves separated by ribs, the ribs on said drum and on said sleeve being in alignment, said sleeve being formed with an opening extending therethrough from each groove therein, means for introducing iiuid to be ltered to the outside of said sleeve, means for withdrawing filtered iluid from the interior of said drum, means providing a chamber having limited peripheral extent adjacent to the outside of said sleeve, means for maintaining a pressure in said chamber lower than that of the iiltered iiuid within said drum, and means for rotating said drum and sleeve so as to bring the openings in said sleeve successively into communication with said chamber, whereby counter-flow of fluid takes place through successive portions of said filter means from` within said drum to said chamber.

4. In a lter, a casing, a drum rotatably mounted in said casing, said drum being formed with a plurality of circumferentially spaced openings therethrough, filter means comprising a wire having a diameter of less than 0.25 mm. spirally wound on said drum and over said openings, adjacent turns of said Wire being spaced apart less than 0.025 mm., means for introducing fluid to be ltered to one side of said drum, means for withdrawing filtered fiuid from the other side of said drum, means providing a chamber having limited peripheral extent adjacent to said one side of said drum, means for maintaining a pressure in said chamber lower than that ofthe ltered iiuid, and means for rotating said drum so as to bring sai-d openings successively into communication with said chamber, whereby counteriiow of iluidv through successive portions of said filter means takes place into said chamber.

5. In a lter, a casing, a drum rotatably mounted in said casing, said drum being formed with a plurality of circumferentially spaced openings therethrough, filter means comprising a wire having a diameter of between 0.1 mm. and 0.25 mm. spirally wound on said drum and over said openings, adjacent turns of said wire being spaced apart between 0.01 mm. and 0.025 mm., means for introducing iiuid to be ltered to one side of said drum, means for withdrawing iiltered uid from the other side of said drum, means providing a chamber having limited peripheral extent adjacent to said one side of said drum, means for maintaining a pressure in said Vchamber lower than that of the ltered iiuid, and means for rotating said drum so as to bring said openings successively into communication with said chamber, whereby counteriiow of uid through successive portions of said filter means take place into said chamber.

AUGUST GUNNAR FERDINAND WALLGREN. 

